This invention relates to a fixing device. More particularly, this invention relates to equalizing the temperature across the fixing device.
In imaging devices, such as electrophotographic printers or copiers, images are formed on media using particles of a pigmented material, such as toner. The toner is bonded to the surface of the media through the application of heat and pressure using a heating device, such as a fixing device. A thermal load is applied to the fixing device from contact with the media during fixing. The temperature on the surface of the fixing device drops in regions contacting the thermal load. If the thermal load is not uniform across the surface of the fixing device, a non-uniform temperature distribution will result. For example, passing narrow width media (such as envelopes, postcards, or even letter size media when used in an electrophotographic imaging device capable forming images on larger sizes of media) through the fixing device will lower the temperature (relative to the temperature before contact with the media) on the surface of the fixing device in areas that contact the media, while areas on the surface of the fixing device outside the width of the media will have a higher temperature (relative to the temperature before contact with the media).
Typically, the temperature on the surface of the fixing device within the media path is controlled using negative feedback. In response to an application of the thermal load, the power supplied to the fixing device is increased in an attempt to offset the drop in temperature resulting from application of the thermal load. However, those areas on the surface of the fixing device not in contact with the media can increase in temperature (depending upon the location of a temperature sensor used in the feedback) because of the increase in power supplied to the fixing device. The high temperatures that result may be sufficient to damage the fixing device. A need exists for a heating device that can achieve improved temperature equalization across its surface.
Accordingly, a method has been developed to reduce a temperature differential on a heating device. In an imaging device, the method for reducing the temperature differential on a heating device, includes supplying power to the heating device to generate heat. The method further includes contacting the heating device with media. In addition, the method includes transferring the heat through a heat pipe to reduce a magnitude of the temperature differential.
A heating device for providing heat to media in an imaging device, includes a heat pipe. In addition, the heating device includes a heating element arranged to provide heat to the media. The heat pipe includes an arrangement to provide heat to a first region of the heating element thermally loaded by the media and includes an arrangement to receive heat from a second region of the heating element thermally unloaded by the media. Furthermore, the heating device includes a support member arranged to provide mechanical support to the heat pipe and the heating element.
A fixing device includes a heat pipe and a support member arranged to provide mechanical support to the heat pipe. In addition, the fixing device includes a heating element and a reflector configured to reflect heat from the heating element. Furthermore, the fixing device includes a film contacting the heat pipe and surrounding the heat pipe and the support member. The reflector includes a position to reflect the heat from the heating element onto the film.
A fixing device includes a heat pipe and a heating element. The heat pipe also includes an arrangement to transfer heat from the heating element into the heat pipe and to transfer the heat from the heat pipe into the heating element. The heat pipe further includes a support member arranged to provide mechanical support to the heat pipe and the heating element. In addition, the heat pipe includes a film surrounding the heat pipe, the heating element, and the support member.